I know carbs have a protein sparing effect, but I am unsure about fats and especially medium-chain triglycerides since they are oxidized by the liver in a manner similar to carbs. I was hoping Lyle could chime in, or someone with some physiology background on this issue.

''First let's sum up what we want to do in terms of maximizing bodyfat loss during a diet. In the most general sense, we want to accelerate the rate of fat utilization by the body. Not only does this increase fat loss, it will exert a protein sparing effect. Let's look at how we might accomplish this dietarily.
By using MCT or DAG, we can provide dietary fatty acids to tissues like the liver and muscle at a more rapid rate. (...)''

Seeing that MCTs are a preferred source of fuel and cant be stored, this would essentially spare protein.
If you body is burning fat "mct" as a fuel as opposed to breaking down its own tissue, then MCT is sparing protein.